1. Field of the Invention
The field relates to detection of failing electrical components in a moving part, e.g. on board a rotor of an AC generator or other motive unit comprising parts that move relative to one other.
2. Description of the Related Technology
A common configuration of synchronous AC generators involves using an auxiliary AC generator mounted on the same shaft as the main generator field to provide excitation current for the main generator field winding. The auxiliary generator is generally known as a rotating exciter. In this arrangement the exciter typically has a 3 phase rotating armature connected to a 3 phase rotating diode rectifier which converts the AC exciter output to DC for feeding to the main generator field winding.
It is common practice to use two series connected diodes in each limb of the rotating rectifier. This ensures that if any one diode fails, such that it becomes conducting in reverse bias mode then the healthy second diode in the limb will block reverse current allowing the exciter-rectifier arrangement to continue providing excitation current to the main generator field winding. If the second diode in the particular rectifier limb fails in the same way then the rotating exciter effectively sees a line-to-line short circuit which can cause serious damage to the machine.
Some embodiments provide an indication, e.g. to maintenance personnel, when a single electrical component (for example a diode) fails so that the faulty component can be replaced before a further failure that could cause serious damage.